1. Field of the Invention
The present invention relates to an improved battery pack and an improved battery-using equipment that includes a battery compartment having an engagement portion engaged with a concave portion of the battery pack.
2. Related Background Art
The structure of a currently, commercially available secondary battery-using equipment for fixing a secondary battery pack to a battery compartment will be described with reference to FIGS. 1A and 1B. FIG. 1B is a sectional view taken along line 1B-1B shown in FIG. 1A.
In FIGS. 1A and 1B, reference numeral 10 denotes a battery pack, 11 denotes a case of the battery pack 10, 12 denotes a secondary battery, 13 denotes a control substrate, 14 denotes a protection apparatus, 15A denotes a battery positive (+) contact, 15B denotes a battery T contact, 15C denotes a battery negative (−) contact, and 16 denotes a concave portion that acts, together with an engagement portion 25 to be described later, as an insertion error prevention function.
Further, reference numeral 20 denotes a battery compartment, 21 denotes an outer wall of the battery compartment 20, 23A denotes a positive (+) connection terminal, 23B denotes a T connection terminal, 23C denotes a (−) connection terminal, 24 denotes an ejection spring, 25 denotes an engagement portion that is engaged with the concave portion 16 to thereby prevent the battery pack 10 from being erroneously inserted into the battery compartment 20, 27 denotes a lock lever, and 28 denotes a lock spring.
FIG. 4 illustrates the internal circuit configuration of the battery pack 10. In FIG. 4, reference numeral 12A denotes a positive (+) electrode of the secondary battery 12, 12B denotes a negative (−) electrode of the secondary battery 12, and 18 denotes a thermistor mounted on the control substrate 13.
The battery pack 10 is constituted as follows. The control substrate 13 and the protection apparatus 14 are arranged in the battery pack 10, i.e., around the secondary battery 12 so as to avoid an increase in a volume of the battery pack 10 as much as possible. The concave portion 16 is arranged in an outer portion of the battery pack 10 on which the control substrate 13 and the protection apparatus 14 are not arranged, so as to have a predetermined length in a direction from an insertion end toward an insertion direction. The battery pack 10 is packed with the case 11 that holds the battery positive (+) contact 15A, the battery T contact 15B, and the battery negative (−) contact 15C. The battery pack 10 thus constituted will be referred to as “secondary battery pack” (battery pack) according to the present invention.
In FIG. 4, the positive (+) electrode 12A of the secondary battery 12 is electrically connected to the control substrate 13 whereas the negative (−) electrode 12B thereof is electrically connected to the control substrate 13 through the protection apparatus 14. The battery positive (+) contact 15A, the battery T contact 15B, and the battery negative (−) contact 15C are electrically connected to the control substrate 13.
The secondary battery 12 is protected by the protection apparatus 14 so that it electrically shuts off the secondary battery 12 from an excessive current when the excessive current flows. The circuit blocks off the control substrate 13 when an excessive charge voltage is impressed and a battery voltage of the secondary battery 12 declines exceedingly, and thereby protects the secondary battery 12. By allowing the thermistor 18 on the control substrate 13 to output an internal temperature of the battery pack 10 as a resistance, a state of the secondary battery 12 can be determined.
Referring to FIGS. 1A and 1B, if the battery pack 10 is normally inserted into the battery compartment 20, the engagement portion 25 enters the concave portion 16. During this insertion, a tapered portion 27a of the lock lever 27 is pressed against the insertion end of the battery pack 10. Due to this, the lock lever 27 is slid downward in FIGS. 1A and 1B against an urging force of the lock spring 28. If the battery pack 10 is completely inserted into the battery compartment 20, the lock lever 27 is moved by a spring force of the lock spring 28 to press a rear end face of the battery pack 10 (slid upward in FIGS. 1A and 1B), thereby preventing the battery pack 10 from being ejected from the compartment 20. In this state, the battery positive (+) contact 15A is electrically connected to the positive (+) connection terminal 23A, the battery T contact 15B is electrically connected to the T connection terminal 23B, and the battery negative (−) contact 15C is electrically connected to the negative (−) connection terminal 23C, whereby the battery pack 10 is electrically connected to the battery compartment 20.
When the battery pack 10 is to be detached from the battery compartment 20, the lock lever 27 is moved to be away from the rear end face of the battery pack 10 (slid downward in FIGS. 1A and 1B) to thereby eject the battery pack 10 from the battery compartment 20 by a spring force of the ejection spring 24. In case that the battery pack 10 is inserted into the battery compartment 20 in a direction different from the predetermined insertion direction, the case 11 of the battery pack 10 abuts against the engagement portion 25. As a result, the battery pack 10 cannot be inserted further, thereby making it possible to prevent the erroneous insertion of the battery pack 10. The same configuration is disclosed by Japanese Patent Application Laid-Open No. 2002-287225.
With the configuration of the conventional battery pack 10 described above, when the battery pack 10 is completely inserted into the battery compartment 20, the lock lever 27 is moved by the force of the lock spring 28 to press the rear end face of the battery pack 10, thereby preventing the ejection of the battery pack 10. That is, since the engagement of the battery pack 10 is made rearward in the insertion direction of the battery pack 10, it is disadvantageously required to enlarge the battery chamber 20 by as much as a thickness of the lock lever 27 in the insertion direction.